RENAL CALCULUS.
The impaction or retention of stone or gravel in the kidney and its surgical treatment will now be considered. It will be necessary to offer some remarks as to the views that have been advanced and are entertained relative to the formation of these bodies, their varieties as well as the changes they undergo, and the different positions they occupy in the gland.
Though it is in the bladder that the larger proportion of calculi grow and attain that bulk which renders them at present unamenable to any other than surgical treatment, it is in the kidneys they for the most part take their origin and from whence the nuclei of these con cretions are mainly derived. Apart from the fact that many stones are prevented leaving the kidneys, where they increase in size and reach considerable dimensions, to the great detriment of the tissue in which they are lodged, the former consideration is sufficient to call for some general observations.
Urinary calculi may be said to be formed (1) by the aggregation and consolidation of certain constituents of the urine which it is the province of the kidneys to eliminate—of these I may instance uric acid, and oxalate of lime, and less frequently cystin, carbonate of lime, and some rarer substances; and (2) by the aggregation of inorganic particles precipitated from the urine as a product of its decomposi tion. The latter concretion consists of the phosphate of lime and the ammoniaco-magnesian phosphate. Hence relative to the urine all calculi may be said to be either of primary or of secondary origin.
It is not within the province of this article to discuss the physio logical modes in which the constituent particles of the primary group take their commencement, but it may be assumed that in the process of their elimination they all pass through the kidney, where they are liable to concrete. So far as the secondary group is concerned it is sufficient to say they are capable of being produced wherever it is possible, within the limits of the apparatus, for the urine to stagnate and undergo ammoniacal decomposition. Though not necessary in the case of primary calculi, the presence of a nucleus, upon which the particles may in the first instance range themselves, is essential in the secondary. Hence the latter forms the material all bodies are coated with, which are foreign to the urinary apparatus, such as bougies, catheters, pins, needles, bootlaces, feathers, and calculi of the primary group, when they have remained sufficiently long in contact with the urine to set up the amount of inflammation necessary for the pro duction of the ammoniacal decomposition of the fluid. Hence under such circumstances the secondary process of calculus formation may be observed, and, if required, artificially demonstrated.
Calculi may be divided into three groups : (1) pure specimens of primary formations, as uric acid, or oxalate stones ; (2) specimens consisting of more than one variety of primary constituent, as, for instance, a calculus partly composed of uric acid and partly of oxalate of lime, and (3) mixed stones or alternating calculi, where the primary constituent, we will say of oxalate of lime, has assumed such dimen sions or shape as to excite inflammation in the part in contact with it sufficient to produce ammoniacal decomposition of the urine; then the stone will become encased with a covering like plaster of Paris composed of a mixture of the phosphate of lime and the ammoniaco magnesian phosphate. Practically all calculi may be thus grouped.
will now be necessary to consider the mode in which the minute organic particles or crystals of which these con cretions mainly consist are in the first place drawn together and con solidated into masses of various density. To understand this clearly is the keystone to the prevention of these formations.
Considerable light has been thrown on the subject by the re searches of Rainey, Ord, and Vandyke Carter. " These observations point to the probability of stone being formed in the urinary passages by the concurrence of conditions which, though not necessarily in themselves morbid, may be said to contribute toward the production of that which is hurtful. They may be briefly summarized as tending to show that some salts, in the presence of a colloid material such as gum or albumin, yield, not crystals, but certain bodies to which Carter has applied the term "submorphous," having the peculiarity of adhering not only to existing surfaces, but also to each other, in laminar series. In the urine may constantly be observed lithates presenting an appearance similar to these submorphous forms, and the presence of an organized material partaking of the nature of a colloid has been demonstrated as existing in a large proportion of urinary calculi. In reference to the production of a calculus by molecular coalescence, Dr. Vandyke Carter remarks : " Regarding first the probabilities of the case, it seems to me that the necessary conditions for the operation of molecular coalescence may at times occur in the living human subject; thus an excess of mucus, perhaps altered in character in the urinary passages, or the effusion of albumin, fibrin, or blood and the like, say from congestion of the kidneys or from irritation of the urinary tract, would furnish a colloid medium, with which uric acid, the urates or oxalates themselves, perhaps in excess, could combine in the manner before described." Added to this is a note from Riudfleisch (Vol. II., p. 143) : "I have long been in favor of the view that the epithelial cells with which the straight tubes are lined generate a colloid material in their protoplasm, which they pour out in the interior of the tubes." Carter further observes, relative to this process : " With regard to some shell structures, it will be sufficient to remark that compact and even incipient layers often bear such a close resemblance to the product of experiment that it is affirmed the intervention of cell influence is not needed to account for their formation (Rainey and Harting) ; and some of these layers being very similar in character to those found in urinary calculi, the inference is again in favor of the latter originating in a manner essentially identical." Analogical evi dence of this kind tends, therefore, to support the view of the non vital origin of the submorphous structures named, notwithstanding their association with living organisms, or with matter once part of such.